# Objective
- As discussed in
https://github.com/bevyengine/bevy/issues/17276#issuecomment-2611203714,
we should transform the cursor's hotspot if the user is asking for the
image to be flipped.
- This becomes more important when a `scale` transform option exists.
It's harder for users to transform the hotspot themselves when using
`scale` because they'd need to look up the image to get its dimensions.
Instead, we let Bevy handle the hotspot transforms and make the
`hotspot` field the "original/source" hotspot.
- Refs #17276.
## Solution
- When the image needs to be transformed, also transform the hotspot. If
the image does not need to be transformed (i.e. fast path), no hotspot
transformation is applied.
## Testing
- Ran the example: `cargo run --example custom_cursor_image
--features=custom_cursor`.
- Add unit tests for the hotspot transform function.
- I also ran the example I have in my `bevy_cursor_kit` crate, which I
think is a good illustration of the reason for this PR.
- In the following videos, there is an arrow pointing up. The button
hover event fires as I move the mouse over it.
- When I press `Y`, the cursor flips.
- In the first video, on `bevy@main` **before** this PR, notice how the
hotspot is wrong after flipping and no longer hovering the button. The
arrow head and hotspot are no longer synced.
- In the second video, on the branch of **this** PR, notice how the
hotspot gets flipped as soon as I press `Y` and the cursor arrow head is
in the correct position on the screen and still hovering the button.
Speaking back to the objective listed at the start: The user originally
defined the _source_ hotspot for the arrow. Later, they decide they want
to flip the cursor vertically: It's nice that Bevy can automatically
flip the _source_ hotspot for them at the same time it flips the
_source_ image.
First video (main):
https://github.com/user-attachments/assets/1955048c-2f85-4951-bfd6-f0e7cfef0cf8
Second video (this PR):
https://github.com/user-attachments/assets/73cb9095-ecb5-4bfd-af5b-9f772e92bd16
e8cd12daf4